Southern diesel electric locomotive

[class37418stag]

Hello everyone

 

I has read information about class 71 later rebuilt class 74 but class 71 & class 74 was more powerful than class 73

 

Why BR ordered class 71 & 74 to scrap as withdrawn over what ?

 

Too noise engine as running line by through the night by while resident can’t sleep

OR

Poor maintenance

OR

Few times by broken down by problem of engine

 

Thank you

[woodenhead]

The Class 71 came first to run express services between Victoria and the Kent coast plus freight work.

 

However some became surplus to requirements as worked dried up and BR needed more Electro-diesels so some were converted to Class 74 to work Southampton and Weymouth boat trains which need motive power off the electric network.

 

Eventually all became redundant because of further reductions in work for them and the 73 was more a more flexible package and they also had plenty of class 33s.

[SRman]

The Class 71 came first to run express services between Victoria and the Kent coast plus freight work.

 

However some became surplus to requirements as worked dried up and BR needed more Electro-diesels so some were converted to Class 74 to work Southampton and Weymouth boat trains which need motive power off the electric network.

 

Eventually all became redundant because of further reductions in work for them and the 73 was more a more flexible package and they also had plenty of class 33s.

 

Adding to that, the 74s had more powerful diesel engines than class 73, from Paxman, but these and all the new electronics used made them rather unreliable.

 

Class 71s were acknowledged as very good locomotives but the work dried up (as stated above) and the 71s were too inflexible as straight electrics; if the power was turned off for maintenance works, they had to be rerouted by sometimes long and torturous routes to get to their required destinations. Electro-diesels had no such restrictions.

 

It was eventually decided that class 73 could do most of the work that was required from classes 71 and 74.

[Wickham Green]

 

Adding to that, the 74s had more powerful diesel engines than class 73, from Paxman, but these and all the new electronics used made them rather unreliable.

 

Class 71s were acknowledged as very good locomotives but the work dried up (as stated above) and the 71s were too inflexible as straight electrics; if the power was turned off for maintenance works, they had to be rerouted by sometimes long and torturous routes to get to their required destinations. Electro-diesels had no such restrictions.

 

It was eventually decided that class 73 could do most of the work that was required from classes 71 and 74.

Yes, the electronics were rather ahead of their time and - like most new technology - didn't take well to a railway environment ......... otherwise the 74s were a logical development of the 71s with the flexibility of the 73s which didn't need overhead wiring of the freight yards - but the drop-off in freight traffic rendered anything non-standard redundant. 

 

Oh - perhaps the topic should be re-titled to Electro-Diesel ??!?

Edited April 12, 2018 by Wickham Green

[TravisM]

From what I remember reading previously, the 10 Class 71's that were used for the rebuild into Class 74's were in the worst condition of the original 24 and were in dire need of rebuilding anyway; and the remaining 14 were renumbered back into the original E5000 series rather than leaving gaps in the numbers.  I also recall that Crewe works had issues rebuilding them, took longer than planned and the build quality was questionable.  Also there were issues with the Paxman engines, electronics which others mentioned. 

 

I think the overall plan was to see if the first batch were successful, was to rebuild the rest but with traffic falling especially coal and ferry traffic on the eastern section and boat traffic on the western, the Southern Region found itself with plenty of surplus Class 33's and 73's, so both classes were withdrawn.

[slilley]

There is a  book on the Class 71s & 74s that came out last November, Southern Way Special No 14. Published by Crecy Publishing in Manchester. All you need to know about both classes.

 

http://www.crecy.co.uk/the-southern-way-special-no.-14

 

Best wishes

 

Simon

Edited April 12, 2018 by slilley

[keefer]

i'm not 100% on the details but I think the 74 differed in how the diesel engine powered the loco.

whereas the 73 was fairly conventional in having the engine revs drive the generator according to demand, the 74s engine ran at constant revs so the generator provided a constant 750V supply - this was then controlled using the circuitry and control systems.

The diesel/generator output was effectively a 'replacement' supply of the line voltage otherwise available from the 3rd rail. i.e you had an electric loco with an alternative power source on board, whereas the 73 is more like an electric and diesel-electric loco in the same body

Edited April 14, 2018 by keefer

[009 micro modeller]

the 71s were too inflexible as straight electrics.

Didn't they also have the disadvantage of having to have small pantographs fitted and tram wires in yards, whereas electro-diesels just run on diesel mode in places where the third rail would be unsafe?

[slilley]

i'm not 100% on the details but I think the 74 differed in how the diesel engine powered the loco.

whereas the 73 was fairly conventional in having the engine revs drive the generator according to demand, the 74s engine ran at constant revs so the generator provided a constant 750V supply - this was then controlled using the circuitry and control systems.

The diesel/generator output was effectively a 'replacement' supply of the line voltage otherwise available from the 3rd rail. i.e you had an electric loco with an alternative power source on board, whereas the 73 is more like an electric and diesel-electric loco in the same body

Thats the basics of it. Explained in more detail in Southern Way Special No 14. 

Didn't they also have the disadvantage of having to have small pantographs fitted and tram wires in yards, whereas electro-diesels just run on diesel mode in places where the third rail would be unsafe?

The Class 71s were pantograph fitted for work in certain yards. max speed under the wires 15mph

[SRman]

Didn't they also have the disadvantage of having to have small pantographs fitted and tram wires in yards, whereas electro-diesels just run on diesel mode in places where the third rail would be unsafe?

 

There were pantographs fitted but they weren't small. The use of overhead wiring in certain yards was instead of third rail, and was for the safety of the men working on the ground in those yards.

[The Johnster]

Thats the basics of it. Explained in more detail in Southern Way Special No 14. 

The Class 71s were pantograph fitted for work in certain yards. max speed under the wires 15mph

 

 

15mph is the normal maximum speed in yards and other non-running lines anyway.